Laterally diffused metal oxide semiconductor (LDMOS) devices are used in power application devices because they complement both bipolar devices and complementary metal-oxide-semiconductor CMOS devices through bi-polar-CMOS-DMOS (BCD) processes. For example, LDMOS devices may be used in radio frequency amplifier devices and microwave power amplifier devices to furnish power application functionality. LDMOS devices may rely on a shallow conduction layer formed under a LOCOS (“local oxidation of silicon”) region or a STI (shallow trench isolation) region to handle the higher drain voltage, when the device is biased.
The on-state resistance (“RON”) and the maximum breakdown voltage (“BVDSS”) of the device are two important characteristics of LDMOS designs. These characteristics are important operating parameters of the LDMOS devices, which dictate the applications with which the devices may be utilized. On-state resistance is usually dependent upon the design and layout of the device, the process condition, temperature, drift region length, doping concentration of the drift region, and the various materials used to fabricate the devices. Breakdown voltage is defined as the largest reverse voltage that can be applied to the drain of the transistor without causing an exponential increase in the current.